Carburetor



1958 L VERNE R. voss ETAL 2,846,203

CARBURETOR Filed June 8, 1956 IypRMAL FUEL LEVEL IN VENTORS A TTORNE Y i nited heats caneunuron La Verne R, Voss, Roseville, and Arthur A. Vuylstelte,

Detroit, Mich, assignors to General Motors Corporation, Detroit, Mich a corporation of Delaware Application June 8, 1956, Serial No. 590,250 7 Claims. (Cl. 26136) The present invention relates to charge forming means and more particularly to carburetors for internal combustion engines.

In the operation of an internal combustion engine of the so-called spark ignited variety, the charge of air and fuel is normally formed :by aspirating the fuel from a jet disposed in a stream of air flowing through a charge forming passage. In order to meter the fuel in proportion to the air flow, the fuel jet communicating with a fuel bowl is disposed in the throat of a venturi so that the pressure of the fuel in the jet will cause the fuel to flow therefrom. The pressure of the fuel in the jet is determined by the atmospheric pressure and the difference between the level of the fuel jet and the level of the fuel in the fuel bowl. If this pressure of the fuel is constant the amount of fuel flow will be determined by the mag nitude of the vacuum in the venturi throat. Since this vacuum will be a function of the mass of air flow therethrough, the resultant charge will have a substantially constant air-fuel ratio. However, an engine in an automotive vehicle or similar installation is frequently subjected to acceleration forces and/ or is operating in various inclined positions and, as a result, the level of the fuel in the fuel bowl relative to the fuel jet may vary and produce an inaccurate metering of the fuel.

It is now proposed to provide means to insure more accurate metering of the fuel flow aspirated into the charge by providing a fuel bowl in which the level of the fuel relative to the jet may be maintained substantially constant. This is to be accomplished by feeding the fuel jet from a fuel bowl having overflow ports disposed in the walls thereof. These ports are adapted to maintain the level of the fuel in the fuel bowl substantially constant relative to the fuel jet by allowing the surplus fuel to overflow therethrough for return to the fuel pump. A first group of ports are arranged in a plane normal to the axis of the charge forming passage to regulate the fuel level when the carburetor is in a vertical position. The bowl is also arranged so that when the carburetor operates in an inclined position and a portion of the ports in the first group are above the fuel level, the surplus fuel will overflow the top of the bowl and the fuellevel will still be substantially the same distance from the fuel jet. In addition, a second group of ports may be provided between the ports in the first group and the top of the bowl. The ports in this group will compensate for the ports in the first group that are above the fuel level and thereby maintain the level of the fuel constant relative to the fuel jet even though the inclination thereof is not adequate to cause the fuel to overflow the top of the fuel bowl.

In the one sheet of drawings:

Figure lis a cross sectional view of a carburetor disposed in the normal operating position and embodying the present invention. I

Figure 2 is an end view of the carburetor of Figure 1.

Figure 3 is a cross sectional view similar to Figure l but showing the carburetor in an inclined position.

Referring to the drawings in more detail, the present invention may be adapted for use in any suitable carburetor 10. In the present instance this carburetor 10 is of the so-called downdraft type in which a charge forming passage 12 extends vertically downwardly through a carburetor housing 14 to form an outlet opening 16 in the mounting flange 18' on the bottom of the housing 14. This flange 18 is adapted to be secured to an intake manifold 20 on an internal combustion engine 22 so that the opening 16 will communicate with the induction passage therein. The upper end of the housing 14 may be adapted to have an air cleaner and/or silencer assembly secured thereto.

The passage 12 may have any suitable metering restriction therein such as a venturi 24. This venturi 24 includes a'restricted throat 26 through which the entire supply of air flows. As the air flows through this throat 26 it Will develop a vacuum therein that Will be indicative of the mass of air flow. A throttle valve 28 may be disposed downstream of the venturi 24 to regulate the mass of the charge flowing therepast.

In order to form a combustible charge of air and fuel, a fuel jet 3i interconnected with a fuel bowl 32 is disposed in or adjacent to the venturi throat 26. Although this jet 30 may be mounted in said venturi in fixed relation to the air flow, it has been found advantageous to have the jet 30 movably mounted relative to the air flow so that the air-fuel ratio may be adjusted. Thus as the air flows through said venturi 24 and develops a vacuum, the fuel will be aspirated through said jet 30 and into the charge. The amount of this fuel will be determined by the position or aspect of the jet 30, the amount of air flow and the pressure of the fuel in said jet 30.

In order to maintain the pressure of the fuel in said jet 30 at a substantially constant amount the fuel bowl 32 may be adapted to maintain a substantially constant elevational difference between the fuel level and the fuel jet 30 irrespective of the inclination of the carburetor 10. The present fuel bowl 32 is disposed concentrically about the charge forming passage 12 and is connected to a source of fuel such as a fuel pump by a supply line 33. The pump is adapted to deliver a surplus of fuel to the bowl 32. The fuel bowl 32 has a group of ports 34 disposed in a plane substantially normal to the axis of said charge forming passage 12 and at some predetermined relation to the fuel jet 3! The distance of this plane from the fuel jet 30 determines the pressure of the fuel in the fuel jet 30. The ports 34 are large enough for the surplus fuel pumped into the fuel bowl 32 to overflow into the drain bowl 36 and be returned to the pump inlet by spill fuel line 35. Thus when the carburetor 10 is vertical the fuel level will be substantially coincident wth the plane of the ports 34.

However, in the event the carburetor ltl assumes an inclined position, the fuel will collect on one side of the fuel bowl 32. As a result, a portion of the ports 34a which are on the high side of the fuel bowl 32 will be disposed above the level of the fuel and, consequently, the fuel will not be able to drain therethrough. When the carburetor 10 assumes an extreme inclined position, the fuel will flow over the rim 38 of the fuel bowl 32 and into the drain bowl 36. It may thus be seen that the height of the rim 38 will determine the plane of the fuel level in this inclined position. By a proper arrangement of the elements, i. e., the position of the rim 38 and the jet 30, this head will be substantially the same as the head in the vertical position.

in addition to or instead of the rim 38, a second group of ports 42 may be disposed between the plane of the first group 34. These ports 42 are arranged so that as v the ports 34a on the high side of the bowl 32 rise above the level of the fuel so that the surplus fuel cannot drain therethrough, the ports 42 in the second group will become submerged and will balance the ports 34:: in the first group and thereby maintain the fuel level substantially constant between the extreme positions where the fuel overflows the rim 38 of the fuel bowl.

It is to be understood that, although the invention has been described with specific reference to a particular embodiment thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

The claims:

1. Charge forming means for an internal combustion engine comprising a charge forming passage, a fuel bowl adapted to be connected to a fuel pump for receiving fuel therefrom, a fuel jet disposed in said passage and connected to said bowl for aspirating fuel into the charge in said passage, a group of overflow ports in said fuel bowl to allow surplus fuel to overflow therefrom and maintain the desired elevational relation between said jet and the level of the fuel in said bowl, additional overflow means in said bowl positioned to compensate for said ports that are above the fuel level when said carburetor is in an inclined position to maintain substantially the same desired elevational relation between said jet and the level of the fuel in said bowl.

2. Charge forming means for an internal combustion engine comprising a normally vertical charge forming passage, a fuel bowl adapted to be connected to a fuel pump for receiving fuel therefrom, a fuel jet disposed in said charge forming passage and communicating with said fuel bowl for aspir'ating metered quantities of fuel into the charge flowing through said passage, a group of overflow ports in the wall of said fuel bowl disposed in a normally horizontal plane and positioned to allow surplus fuel to overflow therefrom for return to said fuel pump, said ports being positioned to maintain some pre determined elevational relation between said jet and the fuel in said bowl, the top of said fuel bowl forming additional overflow means to allow surplus fuel to flow therefrom when said carburetor is in some predetermined inclined position, said top being positioned to maintain substantially the same elevational relation between said jet and the level of the fuel in said bowl when said carburetor is in said predetermined inclined position.

3. Charge forming means for an internal combustion engine comprising a normally vertical charge forming passage, a fuel bowl adapted to be connected to a fuel pump for receiving fuel therefrom, a fuel jet disposed in said charge forming passage and communicating with said fuel bowl for aspirating metered quantities of fuel into the charge flowing through said passage, a group of overflow ports in the wall of said fuel bowl disposed in a normally horizontal plane and positioned to allow surplus fuel to overflow therefrom for return to said fuel pump, said ports being positioned to maintain some pre determined elevational relation between said jet and the fuel in said bowl, a second group of ports in the wall of said fuel bowl above said first group of ports, said second group of ports being arranged to compensate for the ports in the first group that may rise above the level of the fuel in said bowl when said carburetor is in an inclined position to maintain a substantially constant ele vational relation between said jet and the level of the fuel in said bowl when said carburetor is in said inclined position.

4. A carburetor for an internal combustion engine comprising a housing having a normally vertical charge forming passage extending therethrough, a fuel bowl disposed substantially concentrically about said charge forming passage and adapted to be connected to a fuel pump for receiving fuel therefrom, a drain bowl disposed about said fuel bowl to collect overflow fuel therefrom for return to said fuel pump, a plurality of overflow ports in said.

fuel bowl disposed in a normally horizontal plane and positioned to allow surplus fuel to overflow therefrom to thereby maintain some predetermined elevational relation between said jet and the fuel level in said fuel bowl, the rim of said fuel bowl forming additional overflow means positioned to allow surplus fuel to overflow therefrom when said carburetor is in some predetermined inclined position, said rim being positioned to maintain substantially the same predetermined elevational relation between said jet and the level of the fuel in said fuel bowl when said carburetor is in said inclined position.

5. A carburetor for an internal combustion engine comprising a housing having a normally vertical charge forming passage extending therethrough, a fuel bowl disposed substantially concentrically about said charge forming passage and adapted to be connected to a fuel pump for receiving fuel therefrom, a drain bowl disposed around said fuel bowl to collect overflow fuel therefrom, a fuel jet disposed in said charge forming passage and connected to said fuel bowl for aspirating metered quantities of fuel into the charge in said passage, a first group of overflow ports in said fuel bowl disposed in a normally horizontal plane and positioned to allow surplus fuel to overflow therefrom to thereby maintain some predetermined elevational relation between said jet and the fuel in said fuel bowl, a second group of overflow ports in said bowl positioned to allow fuel to overflow therefrom when said carburetor is in an inclined position to supplement the ports in said first group to thereby maintain substantially the same predetermined elevational relation between said jet and the level of the fuel in said bowl when said carburetor is in an inclined position.

6. Charge forming means for an internal combustion engine comprising a charge forming passage, 21 fuel bowl disposed concentrically about said passage and adapted to be connected to a fuel pump for receiving fuel therefrom, a fuel jet disposed in said charge forming passage and connected to said fuel bowl for aspirating metered quantities of fuel into the charge in said passage, a group of overflow ports in said fuel bowl positioned to allow surplus fuel to overflow therefrom to maintain some predetermined elevational relation between said jet and the level of the fuel in said fuel bowl, the rim of said fuel bowl being positioned to allow surplus fuel to overflow therefrom when said carburetor is disposed in some predetermined extreme inclined position to maintain the same elevational relation between said jet and fuel level, additional ports in said fuel bowl positioned to allow additional fuel to overflow therefrom when in some intermediate inclined position to thereby maintain substantially the "same predetermined elevational difference between said jet and the level of the fuel in said bowl.

7. A carburetor for an internal combustion engine comprising a housing having a normally vertical charge forming passage extending therethrough, a fuel bowl disposed concentrically about said charge forming passage and adapted to be connected to a fuel pump for receiving fuel therefrom, a drain bowl disposed about said fuel bowl to collect the overflow fuel therefrom forreturn to said source, a fuel jet disposed in said charge forming passage and connected to said bowl for aspirating metered quantities of fuel into the charge in said passage, a first group of overflow ports in said fuel bowl disposed in a plane substantially normal to the axis of said charge forming passage and positioned to allow surplus fuel to overflow therefrom to thereby maintain some predetermined elevational relation between said jet and the fuel in said bowl, the rim of said bowl being positioned to allow fuel to overflow therefrom when said carburetor is disposed in some predetermined extreme inclined position to thereby maintain substantially the same predetermined elevational relation between said jet and the level of the fuel in said bowl when in said inclined position, additional overflow ports in said fuel bowl disposed 5 6 between said first group and said rim to allow an addi- References Cited in the file of this patent tional quantity of surplus fuel to overflow therethrough UNITED STATES PATENTS when said carburetor is disposed in an intermediate inclined position to thereby maintain substantially the same 2,454,974 Mennesson 1948 desired elevational relation between said jet and the level 5 of the fuel in said bowl when in intermediate inclined FOREIGN PATENTS positions. 1,096,649 France Feb. 2, 1955 

